This invention relates generally to micro-machined three dimensional structures, and in particular to micro-machined movable structures.
Conventional bar code scanners are used to scan a surface with a laser beam. Conventional bar code scanners further typically utilize mirrors that are oscillated to permit the laser beam to scan. Conventional mirrors for bar code scanners are relatively large and imprecise.
In order to manufacture smaller and more precise bar code mirrors, micromachining processes are commonly used in which a silicon substrate is micromachined to produce a mirror. However, conventional micromachining processes suffer from a number of limitations.
For example, in micromachining an initially planar substrate using repeated iterations of photolithographic patterning and etching, it is typically desirable to etch the substrate to achieve etch depth variations that are greater than those appropriate for conventional photolithographic patterning methods used in manufacturing integrated circuits. In some cases, the etch depth variation of the substrate may exceed the depth of focus of the optical lithography equipment. The variation in etch depth may also be sufficiently large to preclude the application of a thin, uniform layer of photoresist using the conventional technique of pouring photoresist onto the substrate and then rapidly spinning the substrate to distribute the photoresist. If photoresist is spun onto a surface having significant topography, then the resulting thickness of the photoresist may vary by more than 1000%. As a result, lithography of fine features in uneven photoresist is difficult because of the overexposure of the thinner photoresist regions. However, in typical micromachining applications, it is typically desirable to subsequently pattern such a substrate having significant topography.
An additional complication arises during micromachining if relatively deep recesses are formed on one side of a substrate and then the other side of the substrate is micromachined. Typical vacuum chucks of conventional automatic wafer handling equipment may not be able to hold such wafers due to the uneven micromachined surface.
In order to overcome some of the difficulties of micromachining, a number of so-called merged-mask micromachining processes have been developed. The typical processing steps in a merged-mask micromachining process include forming all of the etching masks onto the substrate, and then micromachining the substrate. In this manner, the etching masks are formed on a substantially planar surface resulting in relatively consistent and even film thicknesses. However, the conventional merged-mask micromachining processes still suffer from a number of limitations.
The present invention is directed to overcoming one or more of the limitations of the existing micromachining processes.
According to one aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes (1) providing a substrate; (2) applying a layer of a first masking material onto the substrate; (3) patterning the layer of the first masking material; (4) applying a layer of a second masking material onto the exposed portions of the substrate, the layer of the second masking material is at least as thick as the layer of the first masking material; (5) patterning the layer of the second masking material; (6) etching the exposed portions of the substrate; (7) etching the exposed portions of the layer of the second masking material; and (8) etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes providing a substrate; applying a layer of a first masking material onto the substrate; patterning the layer of the first masking material; applying a layer of a second masking material onto the exposed portions of the substrate, the layer of the second masking material is at least as thick as the layer of the first masking material; patterning the layer of the second masking material; etching the exposed portions of the substrate; etching the exposed portions of the layer of the second masking material; and etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes providing a substrate; applying a layer of a first masking material onto the substrate; patterning the layer of the first masking material; thin etching the exposed portions of the substrate; applying a layer of a second masking material onto the exposed portions of the substrate, the layer of the second masking material is at least as thick as the layer of the first masking material; patterning the layer of the second masking material; etching the exposed portions of the substrate; etching the exposed portions of the layer of the second masking material; and etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes providing a substrate; applying a layer of a first masking material onto the substrate; applying a layer of a second masking material onto the layer of the first masking material; patterning the layer of the second masking material; applying a layer of a third masking material onto the portions not covered by the patterned layer of the second masking material, the layer of the third masking material is at least as thick as the combined thickness of the layers of the first and second masking materials; patterning the layers of the first and third masking materials; etching the exposed portions of the substrate; etching the exposed portions of the layers of the first and third masking materials; and etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes providing a substrate; applying a layer of a first masking material onto the substrate; applying a layer of a second masking material onto the layer of the first masking material; patterning the layer of the second masking material; patterning the layer of the first masking material; applying a layer of a third masking material onto the portions not covered by the patterned layer of the second masking material, the layer of the third masking material is at least as thick as the combined thickness of the layers of the first and second masking materials; patterning the layers of the first and third masking materials; etching the exposed portions of the substrate; etching the exposed portions of the layers of the first and third masking materials; and etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes providing a substrate; applying a layer of a first masking material onto the substrate; applying a layer of a second masking material onto the layer of the first masking material; patterning the layer of the second masking material; patterning the layer of the first masking material; thin etching the exposed portions of the substrate; applying a layer of a third masking material onto the portions not covered by the patterned layer of the second masking material, the layer of the third masking material is at least as thick as the combined thickness of the layers of the first and second masking materials; patterning the layers of the first and third masking materials; etching the exposed portions of the substrate; etching the exposed portions of the layers of the first and third masking materials; and etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes providing a substrate; applying a layer of a first masking material onto the substrate; patterning the layer of the first masking material; applying a layer of a second masking material onto the patterned layer of the first masking material; patterning the layer of the second masking material; dry etching the exposed portions of the substrate; etching the exposed portions of the patterned layer of the first masking material; and dry etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes (1) providing a substrate; (2) applying a layer of a first masking material onto the substrate; (3) patterning the layer of the first masking material; (4) applying a layer of a second masking material onto the exposed portions of the substrate, the layer of the second masking material is at least as thick as the layer of the first masking material; (5) patterning a fraction of the thickness of the layer of the second masking material a plurality of times; (6) etching the exposed portions of the substrate; (7) etching a fraction of the thickness of the exposed portions of the layer of the second masking material; (8) etching the exposed portions of the substrate; and (9) repeating steps (7) and (8) a plurality of times.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes (1) providing a substrate; (2) applying a layer of a first masking material onto the substrate; (3) patterning the layer of the first masking material; (4) applying a layer of a second masking material onto the exposed portions of the substrate, the layer of the second masking material is at least as thick as the layer of the first masking material; (5) patterning the layer of the second masking material; (6) applying a layer of a third masking material onto substrate; (7) patterning the layer of the third masking material; (8) etching the layer of the third masking material; (9) etching the exposed portions of the substrate; (10) etching the exposed portions of the layer of the second masking material; and (11) etching the exposed portions of the substrate.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes (1) providing a substrate; (2) applying a layer of a first masking material onto the substrate; (3) patterning the layer of the first masking material; (4) applying a layer of a second masking material onto the exposed portions of the substrate, the layer of the second masking material is at least as thick as the layer of the first masking material; (5) patterning a fraction of the thickness of the layer of the second masking material a plurality of times; (6) applying a layer of a third masking material onto substrate; (7) patterning the layer of the third masking material; (8) etching the layer of the third masking material; (9) etching the exposed portions of the substrate; (10) etching a fraction of the thickness of the exposed portions of the layer of the second masking material; (11) etching the exposed portions of the substrate; and (12) repeat steps (10) and (11) a plurality of times.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes (1) providing a substrate; (2) applying a layer of a first masking material onto the substrate; (3) patterning a fraction of the thickness of the layer of the first masking material a plurality of times; (4) applying a layer of a second masking material onto substrate; (5) patterning the layer of the second masking material; (6) etching the layer of the second masking material; (7) etching the exposed portions of the substrate; (8) etching a fraction of the thickness of the exposed portions of the layer of the first masking material; (9) etching the exposed portions of the substrate; and (10) repeat step""s (8) and (9) a plurality of times.
According to another aspect of the present invention, a method of fabricating a three-dimensional structure is provided that includes providing a substrate; applying a layer of a first masking material onto the substrate; patterning the layer of the first masking material; applying a layer of a second masking material onto the patterned first layer of masking material; patterning the layer of the second masking material; dry etching a first group of exposed portions of the substrate for a first time period; etching the exposed portions of the layer of the first masking material; and dry etching a second group of exposed portions of the substrate for a second time period; wherein the first time period and the second time period are a function of the size of the exposed portions of the substrate.
According to another aspect of the present invention, a method of micro-machining a substrate is provided that includes wet etching the substrate using a merged-mask micro-machining process and dry etching the substrate using a merged-mask micro-machining process.
According to another aspect of the present invention, a method of creating multiple masking layers for use in micro-machining a substrate is provided that includes applying a layer of an etch resistant material onto the substrate and eroding different areas of the layer at different rates to form a multiple thickness layer.
According to another aspect of the present invention, a method of micromachining a substrate is provided that includes using a combination of different etchants having different anisotropic properties.
According to another aspect of the present invention, a method of micromachining a substrate is provided that includes decoupling a first etching process from a second etching process.
According to another aspect of the present invention, a mirror assembly is provided that includes a mirror, a top cap and a bottom cap. The mirror includes a mirror support structure, a pair of T-shaped hinges coupled to the mirror support structure and a mirrored plate coupled to the T-shaped hinges. The mirrored plate includes one or more travel stops for limiting movement of the mirrored plate. The top cap is coupled to one side of the mirror. The top cap includes a top cap support structure including an opening for permitting light to reflect off of the mirrored plate and one or more travel stops coupled to the top cap support structure for limiting movement of the mirrored plate. The bottom cap is coupled to another side of the mirror. The bottom cap includes a bottom cap support structure including an opening and one or more travel stops coupled to the bottom cap support structure for limiting movement of the mirrored plate. The mirror is fabricated using a process comprising a merged-mask micro-machining process.
According to another aspect of the present invention, a mirror assembly is provided that includes a support structure, a pair of T-shaped hinges coupled to the support structure and a mirrored plate coupled to the T-shaped hinges. The mirrored plate includes one or more travel stops for limiting movement of the mirrored plate. The mirror is fabricated using a process comprising a merged-mask micro-machining process.
According to another aspect of the present invention, an apparatus is provided that includes one or T-shaped springs and a mass coupled to the T-shaped springs. The apparatus is fabricated using a merged-mask micro-machining process.